In a conventional paging receiver, a selective call is carried out by adopting time-divisional frames provided subsequent to a preamble and a synchronization code, wherein one of the frames is assigned to a corresponding one of paging receivers.
In the conventional paging receiver, a voltage is applied from a stabilizing power supply to a radio receiving unit to receive a selective call signal for a period of a frame assigned to the paging receiver and a ready period preceding the period of the assigned frame. Thus, a RF amplifier, a local oscillator, a demodulator, etc. in the radio receiving unit start to be risen-up for an intermittent receiving operation to be followed by being applied with a voltage rising up in level during the ready period, and is stabilized to demodulate the selective call signal by being applied with a voltage completely risen-up in level during the period of the assigned frame. Consequently, the electric power consumption in the stabilizing power supply is suppressed to some extent in the paging receiver by adopting the intermittent receiving operation.
In the conventional paging receiver, however, there is a disadvantage in that there is limitation in the suppression of the electric power consumption, because the ready period is fixed to have an appropriate margin of time in view of the situation where the rising-up period of a voltage to be supplied to the radio receiving unit is different among paging receivers. This results in the short life of batteries.